1. Field of the Invention
The present invention is directed to a live well aeration system, and more particularly, to a system in which a pump is used to pump water from a sea chest to a bait well containing live bait.
2. Description of the Related Art
When fishing from a boat, particularly a large or commercial fishing boat, it is a common practice to bring along bait fish in tanks known as live wells. In order to keep the bait fish alive for many hours, it is conventional to employ a pump for continuously pumping oxygenated water from outside the boat to the bait well containing live bait to replace water as the oxygen is being depleted by the bait fish. The live well typically has an overflow which allows displaced water to flow out of the live well and be discharged back to the ambient water.
Typically, the thru-hull aerator includes a pumping means which includes a through-transom fitting mounted in the boat transom below the normal water line and a pump mounted inside the boat on a fitting with a hose leading from the pump to the live well. Generally, the fitting is mounted below the planing surface so that the thru-hull fitting draws fresh water from outside the hull.
When the pump is associated with some means for introducing additional air into the water, the pump is referred to as an aerator. Several distinct types of aerators have been developed.
For example, U.S. Pat. No. 3,822,498 teaches an aerator for a live well wherein water is sucked through a pump and sprayed out a distributor manifold in the form of small jets above the surface of the water. As the jets pass through the air and then strike the surface of the water, the water picks up oxygen.
Many aerators and aerator systems utilize centrifugal rotary bilge pumps, which are well known in the art. In aerators and aerator systems which employ centrifugal bilge pumps as pumps (which are not self-priming), airlock in the pump can be a frequent problem. Airlock can be a particularly significant problem in thru-hull aerator installations. If the supply of water through the thru-hull fitting is not adequate (i.e., when the water intake fitting rises above the water level or when rough water causes the water intake to be exposed to the air), a pocket of air develops in the pump impeller, the pump loses it's prime and becomes airlocked. The back air pressure in the impeller pump output lines in combination with the pressure of the outside water at the intake scoop causes an air bubble to be held at the impeller, causing continuous airlock. Once an airlock develops, the pump ceases to pump water, and this condition jeopardizes the bait fish in the live well.
In most instances, airlock is cleared from the pump by turning the centrifugal pump off thus releasing the back pressure of air and allowing the water in the pump outlet hose to descend back through the centrifugal pump, thereby forcing any trapped air out of the impeller chamber. The pump is then restarted, and in theory, but not always in practice, the pump resumes the normal pumping of water. An alternative means to "jump start" an airlocked impeller, especially when the aerator is mounted in the boat transom, is to rapidly drive the boat in reverse thereby forcing water into the uptake fitting and pump chamber to clear the airlock. However, both of these methods are impractical in that they presuppose that the boat operator is aware that the pump has become airlocked. Often, especially with a live well full of bait fish, the time lapse between the pump becoming airlocked and its detection can mean the death of many bait fish.
In order to avoid drag associated with thru-hull fittings, and in order to avoid problems of plugging of the small thru-hull opening when driving through sea weed or sea grass, there has been a trend to using sea chests to communicate between the pump inlet and the ambient water. The sea chest can be considered a downward opening concavity which is intended to remain below the waterline at whatever speed the boat travels, and is generally provided with a grate or sea grass exclusion mechanism. As such, the sea chest is not intended to communicate with the air, and is intended to provide a continuous source of water to the pump. However, in practice, it has been found that a boat traveling at rapid speed will cause significant amounts of air to pass under the hull in the form of bubbles. These bubbles tend to collect in the sea chest and can be sucked into the aerator pump, resulting in airlock.
Numerous attempts have been made over the years to invent an aerator which prevents or relieves airlock. One is an "anti-airlock" pump manufactured by Rule. This pump incorporates a device which is designed to periodically detect whether there is air present at the pump impeller. If air is detected at the pump impeller, the device shuts the pump off, allowing air to leave through the impeller output line. However, this device does not proactively clear the airlock, and the impeller pump may remain airlocked during the interval between testing for airlock.
U.S. Pat. No. 5,632,220 teaches an aerator wherein an air relief outlet is in communication with the impeller housing and upstream of the impeller. When a build up of air causes airlock, the pump loses suction, which causes a valve associated with the air relief outlet to open enabling air to vent and thereby clearing the airlock. However, there is a need for a more simple and direct means for preventing airlock in an aerator which draws water through a sea chest.
In view of the foregoing, it is an object of the present invention to provide an aerator in communication with a sea-chest which eliminates or minimizes the above-mentioned and other problems, limitations and disadvantages.